1. Field of Invention
The present invention relates to a driver and, more particularly, to an impact driver.
2. Related Prior Art
An impact driver is a tool that delivers a strong, sudden rotational and downward force. In conjunction with a toughened screwdriver bit or a socket, an impact driver is often used to loosen a large threaded bolt or nut that is corrosively “frozen” or over-torqued. The direction can be reversed for situations where screws have to be tightened with torque greater than a screwdriver can reasonably provide.
A manual impact driver includes a sleeve provided around a core. The sleeve is much heavier than the core. The sleeve includes a spline formed on an internal face. The core includes a curved groove defined in the periphery. The spline is inserted in the curved groove. Thus, a user can hold the sleeve with one hand and use a hammer to strike the sleeve with the other hand to exert a turning force on the core and any bit attached to the core. The tool translates the movement of the sleeve to the rotation of the core to generate large values of torque. At the same time, the striking blow from the hammer forces the impact driver and the bit down into the screw.
Another type of impact driver uses a motor to automatically deliver rotational forces. These have the advantage of greatly increased speed. They are most often used in construction and manufacturing to replace screwdrivers where speed and operator fatigue are an issue. In some situations however, this type falls short since current designs cannot deliver the downward blow of a manual unit. This can be especially true on very stubborn fasteners. It is a common misconception that motorized impact drivers deliver a downward force when in fact they deliver no downward force at all.
The prior art is focused on provide adequate torque for driving a screw. There is however an important and unaddressed issue to drive a screw into a piece of material precisely in a desired position and direction.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.